RUBIACEAE 1109 
12. Houstonia longifolia Gaertn. Perennial, slender, puberulent or sometimes 
minutely hispid below. Stems usually tufted, erect or ascending, 2-4 dm. tall, simple or 
branched, 4-angled and often narrowly winged : leaf-blades linear or linear-oblong, 1-3 em. 
long, acute or obtusish, slightly revolute, sessile, ciliolate, dark green above, pale beneath : 
hypanthium becoming 1.5-2 mm. high : sepals linear-subulate, 2 mm. long at maturity, 
acute: corolla 8-9 mm. long, pinkish ; tube funnelform, striped with lilac within ; lobes 
ici or ovate-lanceolate, acutish, } as long as the tube: capsules subglobose, 2.5-3 mm. 
igh. 
In rocky or sandy soil, Maine to Ontario, Manitoba, Georgia and Missouri. Spring to fall. 
13. Houstonia tenuifdlia Nutt. Perennial, glabrous or nearly so. Stems tufted, 
diffusely branched, slender, often wiry: leaves 1—5 em. long ; blades varying from ovate to 
spatulate at the base of the stem to narrowly linear or linear-filiform by the revolute mar- 
gins above, acute: pedicels filiform, 5-10 mm. long : hypanthium glabrate, becoming 1-1.5 
mm. high : sepals lanceolate, 1-1.5 mm. long, slightly longer than the hypanthium : corolla 
pale blue or whitish, 4-5.5 mm. long; lobes lanceolate or oblong-lanceolate : capsules 
subglobose, about 2 mm. long. 
In poor dry soil, Ohio to Virginia, Georgia and Alabama. Spring and summer. 
14. Houstonia angustifdlia Michx. Perennial, glabrous or nearly so. Stems 
much branched at the base, the branches diffuse, 1-6 dm. long, stoutish : leaves numer- 
ous ; blades narrowly linear or the lower ones linear-spatulate, 1-4 cm. long, commonly 
clustered : pedicels 1-4 mm. long : hypanthium turbinate at least during anthesis, becom- 
ing fully 2 mm. high: sepals lanceolate, about as long as the hypanthium during anthesis : 
corolla rather salverform, 4-6 mm. long ; lobes oblong or ovate-oblong, pubescent within : 
capsules oblong except the slightly contracted base, fully 2 mm. thick. 
In dry soil or on prairies, Illinois to Kansas, Florida and Texas. Spring and summer. 
15. Houstoniaténuis Small. Perennial, glabrous or essentially so. Stems branched 
at the base, the branches spreading, 1-2.5 dm. long, slender or wiry : leaves rather numer- 
ous ; blades filiform or those of the lower leaves narrowly linear-filiform, 1-2 cm. long: 
pedicels filiform or capillary, 4-11 mm. long: hypanthium turbinate, becoming 2 mm. 
high : sepals lanceolate, as long as the hypanthium during anthesis : corolla 3-4 mm. long ; 
tube very slender; lobes lanceolate: capsules oblong-turbinate, less than 2 mm. thick. 
In dry soil, Texas. Spring and summer. 
16. Houstonia filifolia (A. Gray) Small. Perennial, glabrous. Stems diffusely 
branched at the base, the branches wiry, 0.5-2 dm. long, commonly much branched : leaf- 
blades narrowly linear or subulate by the revolute margins, 0.5-1.5 cm. long: pedicels 
2-10 mm. long, capillary : hypanthium turbinate, becoming I mm. high : sepals lanceolate, 
about as long as the hypanthium : corolla white or purplish, 4-5 mm. long ; tube slender, 
somewhat expanded at the top; lobes oblong-lanceolate : capsules globose-obovoid, 1—1.5 
mm. long. [H. angustifolia var. filifolia A. Gray.] 
In sand, southern peninsular Florida and the Keys. 
17. Houstonia pulvinata Small. Perennial, glabrous, the foliage turning black in 
drying. Stems branched at the base, the branches 8-12 cm. long, angled, densely tufted, 
forming cushion-like masses : leaves numerous ; blades linear, 1-1.5 cm. long, acute, revo- 
lute, more or less curved, sessile: peduncles 1 cm. long or usually shorter : pedicels 1 mm. 
long or usually shorter, or somewhat longer at maturity, the cymes thus relatively dense : 
bracts minute, acute: hypanthium broadly turbinate, becoming 1.5 mm. long: sepals 
triangular-ovate, acute: corolla bluish, 3.5—4 mm. long; tube gradually enlarged ; lobes 
oblong-ovate, about 1.5 mm. long, obtuse, pubescent within: capsules obovoid, fully 2 mm. 
long, slightly notched. 
In sand, peninsular Florida. Summer. 
18. Houstonia salina Heller. Perennial, glabrous. Stems branched at the base, the 
branches prostrate, 1-2 dm. long, branching, more or less strongly winged: leaf-blades 
rather leathery, oblong or linear-oblong, 1-2 cm. long, acutish, revolute, sometimes re- 
flexed or curved : pedicels 1 mm. long or wanting: hypanthium turbinate during anthesis, 
becoming 2.5 mm. high : sepals triangular-ovate or ovate-lanceolate, shorter than the hypan- 
thium : corolla white or pink, 3-4 mm. high, funnelform ; lobes lanceolate or oblong-lan- 
ceolate, pubescent or glandular within, especially near the margins : capsules oblong-obo- 
void, 3-3.5 mm. long. 
In sand on the coast, Texas. Spring. 
4. PÉNTODON Hochst. 
Annual caulescent herbs, with glabrous foliage. Leaves opposite: blades flat, entire ; 
stipules entire, or 2-3-toothed, adnate to the petioles or leaf-bases. Flowers perfect, in 
